1. Field of the Invention
This invention relates to cooking devices, including deep fat cookers or fryers and more particularly, to a gas fired deep fat fryer which is characterized by a tank for containing a cooking medium such as cooking oil or grease, a burner tube extending through the tank wall from a vented tube stub which receives an adjustable orifice nipple that supplies gas to the burner tube, a U-shaped heating loop element of the burner tube located in the tank for directly contacting and heating the cooking medium and a vented stack extending through the tank wall and terminating the heating loop of the burner tube for venting flue gas from the burner tube. Fixed or removable legs are provided on the tank and wheels may be provided on at least one set of legs for enhancing mobility of the gas fired deep fat fryer. A removable or hinged lid may be provided on the tank and an accessory support tray may also be extended from one end of the tank for supporting and organizing such items as cooking implements, dishes, seasoning and accessory items, as desired. In a preferred embodiment, parallel sides of the tank are bevelled at the bottom and the tank includes a drain line and valve in one end for draining the cooking oil or grease from the tank.
One of the problems realized in designing deep fat fryers and particularly, gas fired deep fat fryers, is that of efficiently transmitting heat from a gas fired burner system to the cooking medium, such as oil or grease, placed in a container, which container is normally placed on a frame or platform above the open fire. Conventional burners designed in this manner operate very inefficiently and are highly sensitive to wind and air currents, which can greatly reduce an already inefficient conductive heat transfer from the container positioned above the burner to the cooking medium. Compensation for the inefficiency in indirectly heating the cooking medium by this technique is usually effected by increasing the gas pressure and, therefore, the flame spread and the heat applied to the container, an effort which usually results in even greater difficulty in maintaining the cooking medium at a desired optimum temperature for cooking food in the container.
It has surprisingly been found that a single continuous burner tube having a U-shaped heating loop or element located in a cooking tank or vat in direct contact with the cooking medium, with the heating loop or element fired at one end with a stoichiometric mixture of gas and air and a vented stack extending from the opposite end of the heating loop or element, provides a highly efficient heating system for the cooker.
2. Description of the Prior Art
Various types of gas fired cooking devices are known in the art. Typical of these is the Portable Deep Fryer Assembly detailed in U.S. Pat. No. 3,722,498, dated Mar. 27, 1973, to Clyde H. Kimbrough. The device includes a vertically-extended tube, a heat plate mounted at the top of the tube to contain cooking oil or shortening and designed to accommodate a basket for containing the food to be cooked. The legs are detachably connected to the heat plate and the chimney is connected to the extending tube. An opening is provided in the flame chute portion of the tube and a jet burner is detachably supported and depends from the lower end of the tube by rod members having elongated ends. A source of compressed gas or utility gas is attached to the jet burner to supply fuel to the assembly. U.S. Pat. No. 3,990,433, dated Nov. 9, 1976, to Richard T. Keating, details a "Gas Burner Flame Temperature Amplifier". The device is designed to increase the combustion flame temperature of a partially-aerated atmospheric gas burner heater and the heat transfer from the heater by injection of jets of preheated secondary air into the combusting chamber to help move the flow of burning gases therethrough. A "Deep Fat Fryer" is detailed in U.S. Pat. No. 4,397,299, dated Aug. 9, 1983, to Cecil K. Taylor, et al. The deep fat fryer includes a tank of inverted U-shaped configuration formed in either a single compartment or divided into two compartments by a medial divider shaped from two parallel, spaced panels with an insulated space between the panels. A pair of infrared-type gas burners are positioned adjacent to inner walls of the lower side portions of the tank and receive a measured amount of pressurized combustion air, which is mixed with fuel gas to heat radiant tile elements of the burner and radiate heat against the tank wall, with the combustion air being substantially no more than the minimum amount necessary to complete combustion. U.S. Pat. No. 4,751,915, dated Jun. 21, 1988, details a "Gas Fired Fryer and Gas Fired Burner Useful Therefor". In the device, a conduit extends through a fry pot so as to be immersed in a frying oil. Combustion occurs in an inlet portion of the conduit and products of combustion are exhausted through an outlet portion of the conduit through serpentine channels along certain walls of the fry pot. Insulating panels form outer walls of the channels and a burner designed to create a vortex of air is provided with a minor portion of the gas ignited before a valve controlling a major portion of the gas is open. U.S. Pat. No. 4,913,041, dated Apr. 3, 1990, to Bruce E. Taber, et al, details a "Deep Fat Frying Apparatus". The fryer has an upper heating section with a bottom wall, from which a spaced pair of well sections depend. An electric shortening melter is provided in the fry pot and a solid insulating material panel structure envelops and abuts portions of the well section and defines a heating cavity which receives a dual gas fired burner assembly. Interior surface portions of the panel structure are recessed to define a multi-fast heating flow passage system which extends along and is partially bounded by laterally outwardly-facing, exterior surface portions of the wells. A specially designed mixture supply system is provided to flow a gas-air mixture into each of the gas fired burners for combustion. U.S. Pat. No. 5,402,713, dated Apr. 4, 1995, to James D. King, details a "Gas Fired Deep Fat Fryer" that employs an interior array of heat exchanger tubes arranged in a U-shaped configuration along the sides and back of a vat. The heat exchanger tubes are located in the interior of the vat with the ends attached to the front vat wall. Each heat exchanger tube employs one or more premix burner components which direct combusting fuel and oxygen into the heat exchanger tube from one end. Each heat exchanger tube may have its burners on either end of the tube and the combustion gases produced by the burners travel through the heat exchanger tubes and exit into a combustion channel. The combustion channel directs the gases exiting the heat exchanger tube around and in contact with at least a portion of the exterior wall of the vat and then to an exhaust flue at the rear of the vat. U.S. Pat. No. 5,417,202, dated May 23, 1995, to Joseph A. C. Cote, details a "Gas Fryer Heat Exchanger" which includes multiple heat transfer tubes, each having an inlet end and an outlet end and at least one of the heat transfer tubes extending at a first selected angle. Other heat transfer tubes extend at a second selected angle opposite to the first selected angle and some tubes extend horizontally. At least one mixing plenum having multiple inlet openings and multiple outlet openings, is provided and the heat transfer tubes are sealed in the plenum.
It is an object of this invention to provide a new and improved, single burner tube, gas fired deep fat fryer which effects direct contact between the cooking medium and the burner tube and is thus designed to increase the efficiency of heat transfer between the burner tube and the cooking medium located in a tank or pot which accommodates the primary heat-producing element of the burner tube.
Another object of this invention is to provide a gas fired deep fat fryer which includes a tank, through which is extended a U-shaped heating loop element of a gas fired burner tube of selected length, for directly contacting and heating cooking oil, grease or other cooking medium in the tank.
Still another object of this invention is to provide a new and improved gas fired deep fat fryer which is simple in design and yet operates in a highly efficient manner to transfer heat from a U-shaped heating loop element in a one-piece, relatively short burner tube, to the cooking oil, grease or other cooking medium in a tank, thus optimizing heat transfer directly from the U-shaped heating loop to the cooking medium responsive to the burning of gas at an orifice nipple adjustably positioned in one end of the burner tube and release of burned products of combustion from a vented stack extending from the opposite end of the burner tube.
Still another object of this invention is to provide a gas fired deep fat fryer which includes a tank of selected volume having a tapered bottom and a drain line and valve for removing the cooking medium, which tank is fitted with a U-shaped heating loop forming a segment of a burner tube system, one end of which U-shaped heating loop extends to a burner tube provided with a slidably adjustable gas orifice nipple and the opposite end of which heating loop is vented and extends upwardly as a stack to dispense flue gas. The continuous burner tube is so designed that burning gas at the orifice nipple in the tube stub end of the burner tube extends substantially through the U-shaped heating loop of the burner tube and is exhausted through the stack, to directly heat cooking oil, grease or other cooking medium in the tank and maintain the cooking medium at a selected, substantially constant temperature during the cooking process.